Sheet feeding apparatus



June 18, 1946. w. E. SCHNEIDER, 2,402,453

SHEET FEEDING APPARATUS Filed Oct. 26, 1944 Sheets-Sheet 1 INVENTOR.

HTTORNEY.

June 18, 1946. w. E. sI-INEIDER 0 SHEET FEEDING APPARATUS Filed 001.. 26, 1944 3 Sheets-Sheet 2- oo 5 m 2 N INVENTOR. .3 B Mam Y I HTTORNEY.

June 18, 1946. w. E. SCHNEIDER 2,402,453

SHEET FEEDING APPARATUS Filed Oct. 26, 1944 $Sheets-Sheet s INVENTOR.

- HTTORNEY Penman 18, 1946 SHEET FEEDING APPARATUS I Walter E. Schneider, Pearl River, N. Y., assignor'- to Dexter Folder Company, Pearl River, N. Y., a corporation of New York Application October 26, 1944, Serial No. 560,492

9 Claims.

This invention relates to sheet feeders and more particularly to pile or sheet supply elevating or moving mechanism and control means therefor.

One object of the present invention is to provide a sheet feeder having novel means for intermittently operatin the pile or sheet supply elevating or moving mechanism.

Another object of the invention is to provide a sheet feeder having novel means of smooth and reliable action for controlling the operation of thepile or sheet supply elevating or moving mechanism, and which is readily adjustable while the feeder is in operation to vary the feeding-in level of the pile or sheet supply to suit different stock conditions.

Another object is to provide a sheet feeder having novel mechanism for electrically controlling the operation of the pile or sheet supply elevating or moving means.

A further object is to provide a sheet feeder having novel mechanism for rendering the pile or sheet supply elevating r moving means intermittently effective, and wherein the usual foot clamp for holding the secondsheet on the pile or supply against movement is utilized as the pile or sheet supply height testing member or feeler to control the operation of said mechanism.

The above andfurther objects and novel features of the present invention will more fully appear from the following detail description when the same is read in connection with the accompanying drawings. It is to be expressly understood, however, that the drawings are for the purpose of illustration only, and are not intended as a definition of the limits of the invention, reference for this latter purpose being had primarily to the appended claims.

In the drawings, wherein like reference characters refer to like parts throughout the several views,

Fig. 1 is a vertical longitudinal sectional view of a sheet feeder embodying the present invention and including a pile elevator, said view being taken on the line i-l of Fig. 2 looking in the direction of the arrows;

Fig. 2 is a front elevation of the sheet feeder shown in Fig. 1 with parts omitted for purposes of clearer illustration;

Figs. 3 and 4 are enlarged. detail side elevations of pile elevator control means;

Fig. 5 is a top plan view, partly in section, of

Referring to the drawings, l0 and II indicate the main side frames and I2 and I3 indicate auxiliary side frames of a sheet feeder on which are mounted thevarious movable parts of the feeder, as well as certain stationary parts thereof. The frames ill'and ii are connected together by a front apron or plate I4 bolted or otherwise suitably secured to said frames (Figs. 1 and 2). Extending transversely of the feeder and journalled in suitable bearings in frames H), II and in apron I4 is a shaft having fixed on its opposite ends winding drums l6. Anchored to each drum iii are corresponding ends of cables i1 and 18 which extend upwardly therefrom at opposite sides of the feeder and'pass over sheaves l9 journalled on frames l0, i llFrom sheaves IS the cables l8 extend rearwardly and pass around sheaves 20 also journalled on frames l0, H (Fig. 1). Cables i1 and I8 then extend downwardly from sheaves l9 and 20, respectively, and have their lower free ends connected to the front and rear ends, respectively, of pile elevator side bars 2| adapted to receive and support a pile board 22 and pile of sheets 23 (Fig. 1). Shaft I5 is intermittently rotated during the operation of the feeder by mechanism to be hereinafter described and which acts to raise the pile elevator step bv step in order to maintain the top of the pile 23 at a proper level for accurate separation and feeding of the sheets one after another therefrom. During upward movement of the elevator the front edge of the pile 23 is guided by spaced vertical guides 24 (Fig. 1) supported in v any suitable manner on tie plate it.

The sheets are separated one 'after another from the top of pile 23, and may be forwarded therefrom either singly in spaced relation, or in the form of a continuous stream of underlapped sheets. As herein shown, separation of the sheets is effected by suction devices 25 (Figs. 1 and 2) of any suitable construction which are adapted to engage opposite rear corner portions of each successive sheet and lift the rear edge thereof 3 hereinafter described, the sheet is winded from below to completely separate the same from the next underlying sheet by sheet winding devices which also act as foot clamps or hold downs and are preferably constructed, mounted and operated as follows. Arranged at the rear and opposite sides of the feeder are foot clamp housings 21 each comprising a main housing member 28 and a cover plate 29 removably secured thereto (Figs' 1 and 2). Housings 2'! are mounted on and capable of adjustment along a pair of transverse shafts 36 having their opposite ends secured in brackets 3| and 32 that are supported on and movable along the tops of frames I 8 and I. Each housing 21 is secured in its various positions of adjustment by a clamp screw 33 threaded in the cover plate 29 and engaging one of the shafts 3|).

cam shaft 34 is provided by a center bracket 35 (Fig. 2) secured to shafts 30.

Disposed within each housing 21 and keyed pn cam shaft-.34 is a cam 38 (Fig. l) engaging a roller,- 3'lfljournalled on one arm 38 of a bell crank lever'39 having another arm 40 projecting forwardly of the housing 21 through a suitable opening in the housing member 26 thereof. Bell crank 39 is. secured to a short sleeve 4| (Figs. 1 and 2) journalled in suitable hearings in housing member 26 and cover plate 29. toward cam 36 by a pull spring 42 having one end connected to arm 38 and the opposite end connected to housing member 28. Pivotally connected at 43 to arm 40 is a cam link 44 having a closed cam groove 45 cooperating with a roller 46 journalled on an arm 4'! formed integrally with housing member 28. Secured to or formed inte grally with link 44 is an arm 48 in which is adjustably secured a downwardly and forwardly extending hollow foot clamp 49.

Through the combined actions of bell cranks 39 and cam grooves 45 in links 44, effected by the springs 42 and cams 36, the arms 48 are moved downwardly and upwardly and at the same time swung about the pivots 43 clockwise and counterclockwise, respectively, once during each cycle of operation of the feeder. This results in a downward forward movement, and a backward upward movement of the foot clamps 49, the downward forward movement being so timed that it occurs after the sheet is lifted, resulting in engagement of said foot clamps with the top of the pile beneath'the lifted sheet to wind and completely float the latter, and to prevent displacement of the underlying sheet, while the lifted sheet is being winded and forwarded. Air under .pressure is delivered to foot clamps 49 through flexible conduits (Fig. 1) which are connected with said foot clamps and with a suitable valve mechanism (not shown) that is, in turn, connected with a suitable source of compressed air.

When the foot clamps 49 are engaged with the top of the pile 23 beneath the lifted sheet as aforesaid, and while air blasts are directed forwardly beneath said sheet, the latter is gripped at the rear thereof by sheet forwarding devices,

Roller '31 is biased r 4 foot clamps 49 are then cut off whereupon said foot clamps are moved rearwardly and upwardly for repetition of the cycle and operation on the next sheet. a

The sheet forwarding devices may be of any type, but as herein shown, are of the suction type and indicated generally at 5| (Figs. 1 and 2).

a The latter are carried in arms 52 fixed on a rock whereupon the sheet is released by the suction devices 25 and forwarded by the sheet forwarding devices from the pile to conveying means hereinafter referred to. The air blasts through pawl carrier 6|.

and is journalled in suitable hearings in brackets 3|, 32 and 35. Shaft 53 is actuated from cam shaft 34 by suitable connections (not shown) to swing-the suction devices 5| rearwardly to engage the lifted and winded sheet, and then forwardly to forward the engaged sheet from the pile. Vacuum is created and broken at predetermined intervals in the suction devices 5| to cause the latter to grip and release each lifted and forwarded sheet, through flexible conduits 54 which are connected with said devices and with a suitable valve mechanism (not shown).

Each sheet gripped by the suction devices 5| is forwarded thereby from the pile and delivered to conveying means indicated generally at 55. The conveying means 55 are driven by any suitable mechanism either at slow speed to enable lapping of the sheets thereon and to advance a stream of the lapped sheets to the printing press or other machine, 01' at fast speed to advance the sheets singly in spaced relation to said press or machine, as well understood in the art. Upon delivery of each sheet to the conveying means 55 by the suction devices 5|, vacuum is broken in said devices which then swing rearwardly to engage the next previously separated and winded sheet.

During normal operation of the feeder the shaft l5 and drums |6 thereon are operated intermittently to raise the pile elevator and pile of sheets 23 at suitable intervals. As herein shown, the intermittent operation of the pile elevator is effected by mechanism comprising a cam 56 (Fi s. 1 and 2) fixed on a transversely extending cam shaft 51 which is journalled in suitable bearings in frames I2, l3, and is driven from the same source of power that drives the hereinbefore'described cam shaft 34. Cam 56 engages a roller 58 journalled on a cam strap 59 extending over shaft 51 and pivotally connected as at with a Roller 58 is biased toward cam 56 by a pull spring 62 having one end connected at 63 with pawl carrier 6| and the opposite end connected to an arm 64. The latter is bolted to a bracket 65 formed integrally with apron 4.

Pawl carrier 6| is preferably mounted for oscillating movement on the hub 86 (Figs. 1 and 2) of a clutch part 61 which is loosely mounted on a short transverse shaft 88 and cooperates with carrier 6| is a pawl ll adapted to continuously engage a ratchet 12 fixed on hub88 of clutch part 61. The clutch, comprising parts 61 and 69, is of well known construction, and is provided to enable disconnecting of the pawl and ratchet mechanism from shaft 68 and rotation of the latter by separate means (not shown) to rapidly lower and raise the pile elevator for loading and reloading purposes. The clutch parts 81, 89 are normally engaged, and may be disengaged by any suitable means, such as, for example, a spoollike member 13 operated in any suitable manner.

Fixed on shaft 68 and adjacent ratchet 12 is a small spur gear 14 (Fig. 2) which meshes with,

on a short transverse shaft 16 journalled in suitable hearings in plate I4 and bracket 65. Shaft 16 has also fixed thereon a small spur gear 11 meshing with a large spur gear 18 fixed on one end of a short transverse shaft 19 journalled in suitable bearing in plate I4 an bracket 65. Fixed on the opposite end of shaft I9 is a small spur gear 80 (Fig. 2) which meshes with a large spur gear 8| that is fixed n the shaft I5. Shaft I also extends through bracket 65 which provides an additional bearing and support for said shaft. Through oscillation of pawl carrier 6| by cam 56 and spring 62, and engagement of pawl 'II with ratchet I2, the shaft I5 and winding drums l6 thereon are thus intermittently rotated through the described gearing between said shaft and shaft 68, thereby imparting step by step ele- I keep the top of the pile at a predetermined level for action thereon by said devices. As herein shown, said control mean preferably comprise a controlled member in the form of a latch 84 v (Figs. 1 and 2) fixed on a short transverse shaft 85 journalled in suitable bearings in frame I3 and. bracket 65. Latch 84 extends forward y above cam strap 59 and is adapted to normally engage the bevelled forward end of a hardened steel block 86 (Fig. 1) secured to the upper surface of said cam strap. Engagement of latch 84 with block 86 holds cam strap 59 against return movement by spring 62, thus preventing roller 58 from following the low part of cam 56 and operation of pawl carrier 6| to engage pawl II with the next tooth on ratchet I2. The high part of cam 56 is so proportioned that upon engagement of the same with roller 58 during each cycle of operation a slight rearward movement is imparted to cam strap 59 to free latch 84 for disengagementfrom block 86 in a manner hereinafter described.

Fixed on shaft 85 adjacent frame I3 is a forwardly extending arm 8'! (Figs. 2 and 4) to which is pivotally connected at 88 the lower end of a vertical link 89. The upper end of link 89 is pivotal- 1y connected at 90 with the core 9| of a solenoid 92 that is bolted to the adjacent frame I 3. When thesolenoid 92. is energized as'hereinafter described,'core 9| is drawn upwardly and thus rocks shaft 85 through the described connections therefor with said; core, whereupon latch 84' is raised out of engagement with block 86 on cam strap 59. The latter is then free tov follow the low part of cam 66 and operate pawl carrier 6| to engage pawl II with the next tooth on ratchet I2, and thereafter partially rotate said ratchet and shaft 88 upon continuedrotation of said cam to raise the-pil elevator and pile of sheets as hereinbe- Extending transversely of the feeder at the rear and one side thereof is a square bar 93 (Figs. 1 and 2) having roun'd end portions 94 and 95 (Figs. 2 and 6) forming journals that are rotatable in bearings formed in center bracket and in a bushing 96 which projects through and is secured in a bracket 91 (Figs. 3, 5 and 6) bolted to the adjacent end bracket 32. Bar 93 extends through fore described. When solenoid 92 is deenergized,

core 9| and latch 84 drop by gravity so that the latter is again positioned in the path of return movement of block 86 on cam strap 59 and prevents said strap from swinging pawl carrier 6| to enable pawl 'II to further raise the elevator and pile of sheets thereon.

a corresponding square opening formed in the pivot sleeve M of one of the foot clamp operating levers 39 so that said bar will be rocked bysaid sleeve in opposite directions when the foot clamp 49 is lowered and raised by said lever into and out, of engagement with the top of the pile as hereinbefore described. Fixed on bar 93 adjacent bracket 91 is a forwardly extending arm 98 Figs. 3, 5 and 6) having journalled thereon a roller 99 adapted to engage curved low and high cam surfaces I00 and II, respectively, formed on the rear face of a fiat circular ring sector I02. The curvature of the front face of sector I02, as well as the curvatures of the low and high cam surfaces I00, IOI, are true radii with respect to the axis of rotation of bar 93.

Sector I02 constitutes the controlling member for the pile elevator and is pivotally mounted at I03 on one arm I04 of a lever I05 provided with an upwardly extending arm I06. Lever I05 is pivotally mounted on the projecting end of bushing 96 between bracket 91 and arm 98 (Fig. 6). Carried in an extension I01 of bracket 91 is a stud I09 (Figs. 3 and 5) through which extends an adjusting screw I09 having threaded engagement with a stud III) carried by arm I06 of lever I05.

Sector I02 engages one end of a plunger pin I I I (Figs. 3 and 5) slidably mounted in a bracket H2 bolted to the adjacent end bracket 32. Threaded in the other end of pin III is a screw II3 the head of which engages the plunger N9 of a normally open micro-switch I I5. The latter is secured within a box I|6 formed integral with bracket II2 and provided with a removable cover II1. Screw I I3 is adjusted so that it just contacts plunger H4, and is locked in adjusted position by a lock nut II8. Micro-switch H5 is so called because the movable contacts. therein require a movement of only a few thousandths of an inch in making and breaking .contact, and

since said switch is well known, and disclosed in the United States Patent No. 1,960,020 granted May 22, 1934, to P. K. McGall, a further description herein is thought to be unnecessary. Switch I I5 and solenoid 92 have connected therewith lead wires H9 and I20, respectively, which are connected with a suitable source of electric current. and said switch and said solenoid are connected together by a lead wire I2I so that when the plunger H4 is actuated by sector I02 to close switch II5 the electric circuit for solenoid 92 will be completed.

With the construction thus described, it will be noted that the foot clamps 49 or at least one of them, in addition to serving as a sheet winding and holding device as hereinbefore described, also acts as a supply or pile height testing member or feeier through engagement thereof with the top of the pile of sheets 23. Accordingly, when the foot clamps 49 are moved toward and away from the pile into and out of engagement with the top thereof, the arm 98=and roller 99, through the described connections therefor with one of said foot clamps, .will be swung downwardly' and upwardly along the low cam surface I00 and toward and away from the high cam surface I M on sector I02. As long as the top of pile 23 is at the proper feeding level, the pile height testing foot clamp 49 will be prevented by the pile from moving downwardly a distance sufllcient to enable roller 99 on arm 98 to engage the high cam surface IN on sector I02. Switch II5 will thus remain open, and the elevator and the operating mechanism for the latter will remain stationary because the pawl carrier 6|, through engagement of latch 84 .Withcam strap 59 will, as shown in Fig. '1, be held in its power stroke position and prevented from returning to enable pawl II to engage the next toothon ratchet I2.

When the height of the pile of sheets 23 decreases through removal of sheets from the top thereof, the roller 99 on arm 98, through increased downward movement of the pile height testing foot clamp 49 is enabled to engage the high cam surface IOI on sector I02 and swing the latter slightly forward about its pivot I03, as indicated in broken lines in Fig. 3, whereupon pin III is moved forwardly and plunger III is actuated to close the contacts of switch H5 and complete the circuit to solenoid 92. The latter isthen energized and draws core 9| upwardly, thereby raising latch 84 out of engagement with cam strap 59 and rendering the pawl and ratchet mechanism operative to raise the pile elevator and pile of sheets 23 thereon as hereinbefore described.

When the pile height testing foot clamp 49 is raised out of engagement with the top of pile 23, roller 99 on arm 98 is swung out of engagement with the high cam surface IN on sector I02, thereupon the contacts of switch II5 automatically open and cause the plunger IIB to return to its original position at which time the pin I I I and sector I02 are also returned to their original positions by said plunger, and the low cam surface I on sector I02 is again engaged with roller 99 on arm 98. Opening of the contacts of switch H5 deenergizes solenoid 92 whereupon core 9| and latch 84 drop by gravity and the latter is again positioned in the path of return movement of cam strap 59, thus rendering the pawl and ratchet mechanism inoperative to further raise the elevator and pile of sheets 23. If the pile of sheets 23 has not been elevated sufliciently,

the above described operations of .the control mechanism and of the pawl ratchet mechanism are repeated upon subsequent lowering of the pile height testing foot clamp 49 until the top of the pile of sheets reaches the proper predetermined height.

The feeding level of the pile of sheets 23 may be varied as desired to accommodate different stock conditions, and this is accomplished by rotating the adjusting screw I09 which may be effected while the feeder is in operation. When screw I09 is rotated in one direction, lever I05 will be rotated in a counterclockwise direction, as viewed in Fig. 3, about its pivot 96, thereby swinging sector I02 in the same direction through an arc concentricwith the axis of rotation of roller arm 98, thus positioning the high cam surface IOI on said sector nearer to roller 99 without disturbing the operating relation between said roller and sector I02 and between the latter and the plunger pin- III. Roller 99 will then engage the high cam surface IOI sooner with the result that the normal feeding levelof the pile of sheets 29 will be disposed in a higher plane. When screw I09 is rotated in the opposite direction, sector I02 will be swung in a clockwise direction (Fig.

3), thereby positioning the high cam surface IOI further away from roller 99 with the result that the normal feeding level of the pile of sheets 23 will be disposed in a lower plane.

If it is desired to raise the pile elevator once during each cycle-of operation of the feeder, as when handling thick sheets, such as, cardboard or fibre board, this may be effected by rotating adlusting screw I09 and swinging sector I02 until the high cam surface IOI is disposed within the completearc of oscillation of roller 99 on arm 98. In this case, roller 99 will merely idle along the high cam surface IOI, micro switch will be held closed by sector I02, and solenoid 92 will be continuously energized to hold latch 84 out of engagement with cam strap 59. The pawl and ratchet mechanism will then operate once during'each cycle of operation of the feeder through continued rotation of cam 58 and the action of spring 62 to raise the elevator and pile of sheets as the sheets are fed one after another from the top of said pile.

There is thus provided a novel mechanism for controlling the operation of a pile elevator in a sheet feeder, which is simple in construction, reliable in its operation, and has relatively few moving parts, none of which has excessive movements. Further, the novel control mechanism utilizes the foot clamp as the pile height testing means or feeler, thus eliminating the necessity of providing a separate feeler and operating means therefor. Additionally, the control mechanism may be regulated while the feeder is in operation to dispose the feeding level of the pile at any desired height, and may also be regulated to render the pile elevator operating mechanism effective to continuously raise the elevator and pile of sheets thereon as the sheets are fed one after another from the top of the pile.

Although a single embodiment of, theinvention has been illustrated and described in the foregoing specification, it is to be expressly understood that changes may be made therein without departing from the spirit and scope of the invention, as will now be clear to those skilled in the art. For example, the foot clamps 69 may be employed solely as foot clamps, and separate stationary blow pipes provided for winding and floating the separated sheets. Also, a duplicate control mechanism may be provided at the other side of the feeder and associated with the other foot clamp whereby operation of the elevator may be controlled by the pile at more than one point thereon. Additionally, the control mechanism may be without modification incorporated in a "continuous type of sheet feeder to control the movement of the supply of sheets which is in the form of a fanned-out bank of sheets, and may be associated with mechanisms other than a pawl and ratchet mechanism, fOr example, a hydraulic mechanism for intermittently raising a pile elevator and a pile of sheets thereon. For a definition of the limits of the invention, reference is had primarily to the appended claims.

What is claimed is:

1. In apparatus of the class described having mechanism for moving a supply of sheets, the combination of means for controlling th operation of said supply moving mechanism comprising a normally stationary pivotally mounted circular ring sector having a cam surface thereon, means under the control of the sheet supply through removal of sheets therefrom for swinging said sector through engagement with the cam surface thereof, and means responsive to the movement of said sector for rendering said mechanism effective to move the sheet supply.

' 2. In a sheet feeder having mechanism for moving a supply of sheets, the combination of means for. controlling the operation of said supply moving mechanism comprising an arm mounted for oscillation about a fixed axis, a roller journalled on said arm, a normally stationary circular ring sector provided with a low and high cam surface concentric with the axis of oscillation of said arm, means pivotally supporting said sector with its cam surfaces in the path of movement of said roller, means engaged with the supply and operable through removal of sheets therefrom for swinging said arm and moving said sector about its pivot through engagement of said roller with the high cam surface thereof, and means responsive to the movement of said sector for rendering said mechanism effective to move the sheet supply.

3. In apparatus of the type having mechanism for moving a suppl of sheets, the combination of means for controlling the operation of said sheet supply moving mechanism comprising an arm mounted for oscillation about a fixed axis. a roller journalled on said arm, a normally stationary circular ring sector provided with a low and high cam surface concentric with the axis of oscillation of said arm, alever pivotally supporting said sector with its cam surfaces in the path of movement of said roller, means engaged with the supply and operable through removal of sheets therefrom for swinging said arm and moving said sector about its pivot through engagement of said roller with the high cam surface thereof, means responsive to the movement of said sector for rendering said mechanism effective to move the sheet supply, and means for adjusting said lever and moving said sector bodily relative to said roller in a path concentric with said axis.

4. In a sheet feeder having mechanism for moving a supply of sheets, the combination of a controlled member associated with said mechanism and movable to render the latter effective and ineffective to move the sheet supply, a nora controlling member having a low and high cam with the high cam surface thereof to effect closing of said switch and energizing of said solenoid, and means engaged with the supply for controlling the movement of said controlling member and closing of the switch thereby.

6. In a sheet feeder having mechanism for intermittently moving a supply of sheets, the combination of means for controlling the operation of said sheet supply moving mechanism comprising a normally stationary movabl mounted surface thereon, afoot clamp, means for periodically moving said foot clamp into engagement with the top of said sheet supply, means normaily engaged with one of said cam surfaces and movable gradually toward the other of said cam surfaces under the control of said foot clamp for moving said controlling member through engagement with said other cam surface thereof when the movement of the foot clamp into engageinent with the supply exceeds a predetermined amount, and means responsive to the movement of said controlling member for rendering the sheet supply moving mechanism effective. 1

7. In apparatus of the type having mechanism for moving .a supply of sheets, the combination of means for controlling the operation of said sheet supply moving mechanism comprising an arm mounted for oscillation about a fixed horizontal axis and having a roller journalled thereon, a normall stationary movably mounted circular ring sector provided with a low and high cam surface concentric with the axis of oscillation of said arm, a foot clamp, mechanism for periodically moving said foot clamp downwardly into engagement with the top of the sheet sup ply, means connecting said arm with said foot clamp operating mechanism for corresponding movement with said foot clamp .whereby said roller is caused to move said sector through engagement with the high cam surface thereof when the downward movement of said foot clamp exceeds a predetermined amount, and means responsive to the movement of said sector for rendering the sheet supply moving mechanism effective.

8. In a sheet feeder having mechanism for intermittently moving a supply of sheets, the combination of means for controlling th operation of said sheet supply moving mechanism comprising an arm mounted for oscillation about a fixed horizontal axis and having a roller journalled thereon, a normally stationary circular ring sectrolled member to render said mechanism effective, and means engaged with the supply for controlling the movement f said controlling memher.

5. In sheet handling apparatus having mechanism for moving a supply of sheets, the combination of a controlled member associated with said mechanism and operable to render the latter effective and ineffective to 'move the sheet supply, means including a solenoid for moving said controlled member to render said mechanism effective, a normally stationary movably mounted controlling member having a low and high cam surface thereon, a normally open electric switch associated with said controlling memher and connected with said solenoid, means normally engaged with the low cam surface of the controlling member and movable gradually toward the high cam surface thereof for moving said controlling member through engagement tor provided with a low and high cam surface concentric with the axis of oscillation of said arm, a lever pivotally supporting said sector with its cam surfaces in the path of movement of said roller, a foot clamp, mechanism for periodically moving said foot clamp downwardly into engagement with the top of the sheet supply, means connecting said arm with said foot clamp mechanism whereby said sector will be swung about its pivot through engagement of said roller with the high cam surface thereof when the downward' movement of said foot clamp exceeds a predetermined amount, means responsive to the movement of said sector for rendering said supply moving mechanism efiective, and means for adjusting said lever and moving said sector bodily relative to said roller in a path concentric with said axis. I

9. In sheet feeding apparatus of the type hav ing mechanism for intermittently moving a supply of sheets, the combination of a controlied 11 member movable in one direction to provide for operation of said mechanism and movable in the opposite direction to discontinue the operation of said mechanism, means including a solenoid for moving said controlled member in said firstnamed direction, an arm mounted for oscillation about a fixed horizontal axis and having a roller Journalled thereon, a normally stationary pivotally mounted circular ring sector provided with a. low and high cam surface concentric with the axis of oscillation of said arm, a normally open switch associated withsaid sector and connected 

